Christopher Odd, hands down.
Discovered him around the time XCOM2 got released, because I was looking for someone to learn a trick or two from. Learned a lot from how he plays tactical games, but stayed for his calm and down to earth way (I absolutely can’t stand that hyper, over-the-top crap that a ton of Let’s Players do). Have also discovered the one or other gem through his videos.
Can only recommend!
Oh, and I also watch a ton of stuff on game design due to an interest into game development and recently did a blog post on my favourites there. To quickly summarise that: The Architect of Games, Design Doc, Game Maker’s Toolkit, GDC, Noclip, Razbuten
Definitely In Other Waters, an earlier work from the same people who recently brought you Citizen Sleeper. It’s a narrative heavy game were you play an AI helping a xenobiologist. You perceive the alien maritime world through a quite minimalistic interface, and nevertheless that game had me on the edge of my seat from the start. Highly recommended, and IMO far too little known.
Currently 70% off and less than 5€. Also available as part of a bundle with Citizen Sleeper.